In conventional rotary compressors, for example, a cylinder chamber is divided into a low pressure chamber and a high pressure chamber by a blade. The low and high pressure chambers are switched to become the high and low pressure chambers, respectively, in accordance with the operation of a compression mechanism. Thus, a suction process in the low pressure chamber, and a compression process and a discharge process in the high pressure chamber are simultaneously performed, thereby compressing low pressure gas, and discharging high pressure gas. In the rotary compressors of this type, the high pressure gas remaining in a discharge port when the discharge process is finished returns to the low pressure cylinder chamber, and re-expands therein when a next compression process is started. This causes significant pressure pulsation near the discharge port. A rotary compressor including a mechanism for reducing vibration and noise caused by the pressure pulsation has been proposed (see, e.g., Japanese Patent Publication No. H08-219051).
The rotary compressor of Japanese Patent Publication No. H08-219051 includes a high pressure fluid injection mechanism for injecting high pressure fluid in a cylinder chamber through a high pressure fluid passage opened in the cylinder chamber after a suction port of a compression mechanism is completely closed by a piston.
In the compressor of Japanese Patent Publication No. H08-219051, the high pressure fluid injection mechanism brings the high pressure fluid (high pressure oil) into contact with gas which re-expanded and caused high frequency pulsation in the hermetic cylinder chamber to cause interference between the high frequency pulsation and high pressure, thereby reducing the high frequency pulsation. This can reduce vibration and noise caused by the high frequency pulsation.